Electrical plugs, both of the male and female type, equipped with replaceable overcurrent-protection devices and the electrical components associated therewith are designed for disposition of the devices intermediate the normal copper prongs of the male plug or the contact blades of the female plug and the conductive extensions of the same for connnecting the latter with the usual electrical equipment. The functioning of such devices are well-known in the art and applicant's co-pending application Ser. No. 121,324 discloses an imporvement of such devices; said application being incorporated in this application by reference.
Since the present invention is readily useful with both male and female electrical plugs, it is to be understood that hereinbelow the term "plug" shall be construed as referring to both types since in the former the conductive components comprise normally outwardly projecting prongs whereas in the latter there are provided internally disposed copper blades for union with the prongs of the associated electrical element. Thus the adaptability of the present invention to either type of plug is readily apparent so that the stated definition of the word "plug" for purposes of this application is fully warranted. In a conventional electrical plug the body thereof is normally formed of insulating material such as a plastic, as PVC, PP, PE, or the like, which material is customarily subjected to expansion, contraction, or other deformation resulting from temperature changes occuring during manufacture or in usage. Additionally, such plugs will be deformed or distorted as a result of externally applied compression or tension forces resulting in adversely affecting the electrical connection with the development of various problems such as inadequate contact performance; non-conductive phenomena; or imperfect conductivity which result in temperature rise with attendant sparking or burning. An effective plug should be constructed to satisfy the usual various types of rigid pre-release tests, such as, for instance, temperature rise tests, overload anti-sparking tests, high current short-circuiting tests, etc. Thus the potential for the development of such problems must be taken into consideration during plug design since without satisfying these tests any plugs would necessarily represent a source of serious danger.